Radiocarbon 14 dating wikipedia
Carbon has an atomic number of 6, an atomic weight of 12.011, and has three isotopes: carbon-12, carbon-13, and carbon-14.(The numbers 12, 13 and 14 refer to the total number of protons plus neutrons in the atom's nucleus.
Their commercial rate (in 2008) is $675.00 per sample, which somewhat limits its accessibility to chronically under-funded archeological research projects.The levels of 14C present in a specimen can be measured in a variety of ways; however the invention of accelerator-based mass spectrometric techniques have drastically increased measurement accuracy, as it provides a count of the number of 14C atoms present in a sample.It has been used to date specimens up to 60,000 years in age.(Since humans have only existed in the Americas for approximately 12,000 years, this is not a serious limitation to southwest archaeology.) Radiocarbon dating is also susceptible to contamination.If the ground in which an object is buried contains particles of coal or other ancient sources of carbon, radiocarbon testing may indicate that the object is far older than it really is.There are eight AMS laboratories currently operating in the Unites States.
In Arizona, virtually all dating is performed by the Arizona Accelerator Mass Spectrometry (AMS) Laboratory at the University of Arizona in Tucson.
Carbon dating produces the most reliable results when multiple samples can be tested to ensure accuracy and limit potential interferences. University of New Mexico Press: Albuquerque, NM, 1994.
Alternative dating techniques such as dendrochronology may be employed to confirm the results of radiocarbon dating.
When an organism dies, the intake of 14C ceases, and what was left in the organism begins a measurable disintegration.
Carbon-14 has a half-life of 5730 years (±40 years), meaning that (in accordance with the law of radioactive decay) it will take that length of time for half of the carbon present in an organism to decay into stable carbon isotopes.
Thus carbon-14 has six protons and eight neutrons.) Carbon-12 is by far the most abundant carbon isotope, and carbon-12 and -13 are both stable.